Organic light emitting diode (OLED) displays often produce a light output having a color that varies with view direction.
U.S. Pat. Appl. Pub. No. 2010/0110551 (Lamansky et al.) describes a multifunctional optical film for enhancing light extraction that includes a flexible substrate, a structured layer, a high index backfill layer, and an optional passivation layer. The structured layer effective uses microreplicated diffractive or scattering nanostructures located near enough to the light generation region to enable extraction of an evanescent wave from an OLED device.
U.S. Pat. No. 8,538,224 (Lamansky et al.) describes a light extraction film having internal nanostructures and external microstructures for OLED devices. The light extraction film includes a flexible substantially transparent film, a low index nanostructured layer applied to the film, and a high index planarizing backfill layer applied over the nanostructured layer. External optical microstructures are applied to the flexible substantially transparent film on a side opposite the nanostructured layer to enhance light extraction from the OLED devices while providing for a more uniform luminance distribution.
U.S. Pat. No. 8,541,778 (Seki et al.) describes a diffraction grating having a transparent supporting substrate; and a cured resin layer which is stacked on the transparent supporting substrate and which has concavities and convexities formed on a surface thereof, wherein when a Fourier-transformed image is obtained by performing two-dimensional fast Fourier transform processing on a concavity and convexity analysis image obtained by analyzing a shape of the concavities and convexities formed on the surface of the cured resin layer by use of an atomic force microscope, the Fourier-transformed image shows a circular or annular pattern.